The present exemplary embodiment relates to industrial machine control and corresponding communication protocols. In one embodiment, the machine control communication protocol is Distributed I/O that has Extended Data Transfer (EDT) capability. It finds particular application with expanding the underutilized bandwidth of the EDT to gather/send secondary input and output data within a control system and will be described with particular reference thereto. However, it is to be appreciated that the present exemplary embodiment is also amenable to other like applications.
Machines in today's industrial environment employ various control mechanisms to provide optimum performance. Thus, data can be received in various forms to control one or more processes. In one example, machines require precision control with regard to motion and therefore control of motor speeds, torques and other parameters. As shown in FIG. 1, this information can be gathered and transmitted via one or more field devices 102, 104, 106, 108, 110 and 112 mounted in proximity to a machine process. The one or more field devices 102-112 can be sensors, actuators, switches, etc. In one example, sensors can measure data including temperature, distance, flow rate, etc. This data can be transmitted and received in various forms including voltage, current, serially, etc.
This transmitted data can be stored and/or processed in a controller 114 such as a programmable logic controller (PLC). The PLC 114 can receive data from the one or more field devices 102-112 via one or more input/output (I/O) terminals 116, 118 at a particular rate. The I/O terminals, 116,118 can provide a hardwire connection for the one or more field devices 102-112 to a respective terminal base 122, 124. In one example, the I/O terminals 116, 118 are screw terminals which accept one or more hardwire connections. The terminal base 122, 124, is coupled to an I/O module 126, 128, that is specific to a particular data type. In one example, the I/O module 126 is an analog input/output module. In another example, the I/O module 128 is a digital input/output module.
The I/O terminals 116, 118 can be located remotely from the PLC 114 and communicate with the field devices 102-112 via network 120 or communication means. Various protocols and/or standards are utilized for the transmission of data in a machine controlled system. These protocols are typically related to a manufacturer of one or more control components, PLC, control devices, and/or data transmission media. In addition, the protocol and hardware associated therewith can be selected based on logistical concerns data location, machine layout, etc. The protocol can include field device help information, data integrity, etc. in addition to actual data values. In this manner, a machine control system can identify and remedy any breakdown in data communication between the field devices and the central controller to provide a more robust control system. An adapter 130 can be employed to provide an interface for communication between the I/O modules 126, 128 and the network. Communication between the terminal base 122 and the terminal base 124 and the terminal base 122 and an adapter 130 can be facilitated via a data interface. The adapter 130 can include a network interface 132 to allow connection to the network 120. The network 120 can employ a particular communication protocol such as EtherNet/IP™, Control Net™, Device Net™, Profibus, etc.
Once the data is received, the PLC can manipulate the data in substantially any manner as set forth in a program. In one example, the data can undergo one or more mathematical operations such as summation, averaging, etc. The PLC 114 programs can be stored and activated based on one or more conditions such as an event, a threshold, etc. Once the program has completed data processing, information can be output from the PLC 114 via one or more output terminals, ports, etc. to the field devices employed to control the machine.
One protocol utilized for machine control is Distributed I/O which is employed with a distributed I/O machine control architecture. Distributed I/O can provide flexibility to allow a designer to use a precise amount of hardware in one or more remote locations for a particular control design. The distributed I/O hardware can be offered in modular block styles. Distributed I/O is a modular I/O that employs a system of interface cards and communication adapters that interface directly to the field not based directly to one or more field devices (e.g., sensors, actuators, switches, etc.) of the machine and communicate their status to the controller via the network 120. In this manner, the designer can mix and match I/O interfaces and communications adapters. For example, a designer can independently select I/O type, termination and network to meet requirements of a particular application.
Typically, a Distributed I/O adapter module (e.g. adapter 130) interfaces one or more Distributed I/O modules (e.g. I/O modules 126, 128) to an I/O scanner port across the communication network. The Distributed I/O adapter module contains a built-in power supply that converts 24V DC to 5V DC for the backplane to power the Distributed I/O module. Distributed I/O adapter modules can be utilized for EtherNet/IP™, ControlNet™, DeviceNet™, Universal Remote I/O, Profibus DP, etc. In one example, an adapter communicates with up to eight I/O modules, allowing connection to two hundred and fifty six digital input/output points or sixty four analog input points/thirty two analog output points, or a combination thereof.
Currently, adapters scan Distributed I/O modules gathering/sending data to the sixteen word area of the Distributed I/O module. One exception can occur when the Distributed I/O module has Distributed EDT capabilities. Usually, the Distributed EDT capability is utilized to send larger configuration data to a Distributed EDT module. Distributed EDT occurs when a MSG construction is sent for the I/O module and this information is not readily available in the adapter 130. Therefore, the adapter 130 sends a Distributed EDT communication that response to the MSG instruction. Usually, this does not occur frequently. Therefore, most of the Distributed EDT bandwidth is underutilized. Thus, what are needed are systems and methods to use this EDT bandwidth to provide additional functionality to the Distributed I/O product family.